Process of applying protecting-glaze to carbon electrodes.



1 (i6- 84 CROSS REFERENCE l-ZXANHNER formed contains acid impurities,such, for

UNITED STATES PATENT OFFICE.

3m L. I. SNYDER, OI CLEVELAND, OHJEO, ASS IGNOB 1'0 NATIONAL CARBON COH-rm, OI CLEVELAND, OHIO, A CORPORATION OF JERSEY;

FROM OR APPLYING PBOTECTING-GLAZE '.l.O CARBON ELECTRODES.

1,000,761. I0 Drawing.

Specification of Letters Patent.

Application filed September- 0, 1910. Serial 1'0. 580,887. I i I l I l pI I 7; I J

Patented Aug.-15, 1911.

To allwkomitmycoacm:

Be it known that I, J osnrn L. K. SNYDER, a citizen of the UnitedStates, residing at Cleveland, in the county of Cuyaho and State ofOhio, have invented a certain new and useful Improvement in Processes ofApplying Protecting-Glaze to Carbon l'll'ectrodes, of which thefollowing is a full, clear, and'exact descri tion.

It has been propose .to apply to carbon electrodes, intended for use inelectric smelting furnaces, a protective coating adapte to prevent theelectrodes from burning away aboveor in the charge in the furnace whenin use. It will be understood that this coating must be made of somematerial such that it will have no detrimental effect upon the charge inthe furnace. Heretofore such protective coatin have been applied to thesurface of cure or baked carbon electrodes. The curing or bakingoperation, however, generally produces upon said electrodes a hard,smooth skin,- and it is very diflicult to get any protective coating 25to adhere tenaciously to such electrodes, particularly when they aresub'ected to the heat and gases in an electric urnace.

The present invention is a process of producing such protective coatingupon such carbon electrodes in a way that will cause them to be sofirmly adherent that they will not come off in the corrosive zone whilethe electrode is in use. I

The process consists in applying to the formed carbon electrode, whileit is in the green, 2'. e., unbaked condition, and while it therefore ofa plastic nature, some material, which, under the influence of the heatemployed to bake or cure the carbon electrodes, or the heat of theelectric furnace in which it is finally used, will, either by fusion orchemical change, produce upon the surface of said electrode a coating ofthe required character.

In carrying out the process according to what I now believe to be thebest specific method of procedure a paste made of a suitable chemicalsubstance and a binder therefor is applied to the surface of the green,2'. e., unbaked formed carbon electrode. A great variety of chemicalsubstances may be employed which should be selected in view. of existingconditions. If, for example, the carbon mix of which the green electrodeis forming with example, as silicious material, the substances mixedwith the binder may be sodium carbonate or some other analogous Basicsalt,

Win10 will combine chemically with. the silicon compounds and form aslag-producing glaze on the surface of the electrode when the greencarbon is subjected to sufficient heat. If the carbon mix contains basicimpurities, such, for example, as ferric oxid,

the substance mixed with the binder may be. a suitable salt, such, forexample, as potassium bisulfate, or borax adapted to com nne w1 sue as1c im 11H 1% and form a slagproduclenf glaze. r some chem cal may beemploy such as will'comblne wlth the carbon itself to form aslag-producing glaze; for example, calcium chlorid may be used c car 11calcium carbid. Pitch and tar are suitable for use as Binders,

but a great variety of other binders may be I, used, as, for example,glucose, glue and water lass.

It is'obvious that when the protecting coating is formed in the mannerabove de- I scribed, it will, because the paste was applied to the greenand therefore plastic car-- i on, he formed partly within the poresthereof; and will, therefore, be so firmly adherent that its removal ispractically im'. possible.

Instead of applying the paste above described, there may be incorporatedin the mix of which the electrode is formed, such chemicals as under theinfluence of the curing heater the heat of the electric furnace when theelectrode is in use will produce the .required glaze on the surfaces.Examples of such chemicals are flour-spar, lime and 4 silica, and sodasalts and silica. It is perhaps not racticalto produce by this specificmeth as thick a protective coating as .by the first method suggested,but on the,

other hand, the coating produced will be even more firmly secured inplace, and will increase in thickness .as the elect-rode is wasted away.Or, instead of applyin the material in the form of a paste or p asticlayer,'suitable material. such, for example, as heretofore mentioned,may be embedded or forced into the suitably prepared surface 1 of thegreen carbon electrode.

The common characteristic of the several methods of procedure abovedescribed is the application to the green. uncured and thereforeplastic, carbon electrode, of such ma- 1" terial as under the influenceof the heat necessary for the curing of the electrode or of the heatgenerated in the electric furnace will produce either by merefusion orby chemical change aslag producin protective coating upon t e surface ofthe e ectrode.

Having described my invention, I claim:

1. The herein described process of ap lying a protective coating to anelectric urnace carbon electrode, which consists in applying to a greenunbaked electrode a su stance such as, when said electrode is subjectedto the required heat, will produce a slag-producin protective coatingonthe surface of said e ectrode; and in then subjecting the electrodewith this material applied to it to the required heat.

, 2. The herein described process of ap ly-r ing' a protective coatingto an electric rnaoe carbon electrode, which consists in ap- 20 plyingto the surface of :1V green unbaked carbon electrode a paste com risinga binder and a chemical such as wil 'under the influence of the curingheat produce a slag forming protective coating on the surface of saidelectrode; su uentiy subjecting said paste-covered electro e to theaction oi the usual curing heat.

In testimony whereof, I hereunto afiix my signature in the J O EPH L. K.SNYDER. Witnesses: 1

D. L. Qnnwar, R. L. Smear.

resence of two witnesses. 30

